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<title>Problem 1672. -- [Usaco2005 Dec]Cleaning Shifts -- 衡阳八中OJ离线版-2012-02-29</title><center><h2>1672: [Usaco2005 Dec]Cleaning Shifts</h2><span class=green>Time Limit: </span>5 Sec&nbsp;&nbsp;<span class=green>Memory Limit: </span>64 MB<br><span class=green>Submit: </span>126&nbsp;&nbsp;<span class=green>Solved: </span>58<br>[<a href='submitpage.php?id=1672'>Submit</a>][<a href='problemstatus.php?id=1672'>Status</a>][<a href='bbs.php?id=1672'>Discuss</a>]</center><h2>Description</h2><div class=content>Farmer John's cows, pampered since birth, have reached new heights of
fastidiousness. They now require their barn to be immaculate. Farmer John,
the most obliging of farmers, has no choice but hire some of the cows to
clean the barn.

Farmer John has N (1 <= N <= 10,000) cows who are willing to do some
cleaning. Because dust falls continuously, the cows require that the farm
be continuously cleaned during the workday, which runs from second number M
to  second number E during the day (0 <= M <= E <= 86,399). Note that the
total number of seconds during which cleaning is to take place is E-M+1.
During any given second M..E, at least one cow must be cleaning.

Each cow has submitted a job application indicating her willingness to work
during a certain interval T1..T2 (where M <= T1 <= T2 <= E) for a certain
salary of S (where 0 <= S <= 500,000). Note that a cow who indicated the
interval 10..20 would work for 11 seconds, not 10. Farmer John must either
accept or reject each individual application; he may NOT ask a cow to work
only a fraction of the time it indicated and receive a corresponding
fraction of the salary.

Find a schedule in which every second of the workday is covered by at least
one cow and which minimizes the total salary that goes to the cows.

</div><h2>Input</h2><div class=content>* Line 1: Three space-separated integers: N, M, and E.

* Lines 2..N+1: Line i+1 describes cow i's schedule with three
        space-separated integers: T1, T2, and S.

</div><h2>Output</h2><div class=content>* Line 1: a single integer that is either the minimum total salary to
        get the barn cleaned or else -1 if it is impossible to clean
        the barn.

</div><h2>Sample Input</h2>
			<div class=content><span class=sampledata>3 0 4  //三头牛,要打扫从0到4号stall<br />
0 2 3  //一号牛,从0号stall打扫到2号,工资为3<br />
3 4 2<br />
0 0 1<br />
<br />
INPUT DETAILS:<br />
<br />
FJ has three cows, and the barn needs to be cleaned from second 0 to second<br />
4. The first cow is willing to work during seconds 0, 1, and 2 for a total<br />
salary of 3, etc.<br />
</span></div><h2>Sample Output</h2>
			<div class=content><span class=sampledata>5<br />
<br />
OUTPUT DETAILS:<br />
<br />
Farmer John can hire the first two cows.(问你最少花多少钱....)<br />
</span></div><h2>HINT</h2>
			<div class=content><p></p></div><h2>Source</h2>
			<div class=content><p><a href='problemset.html?search=Silver'>Silver</a></p></div><center>[<a href='submitpage.php?id=1672'>Submit</a>][<a href='problemstatus.php?id=1672'>Status</a>][<a href='bbs.php?id=1672'>Discuss</a>]</center>﻿<br>

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